CAPE CANAVERAL, Fla. - When SpaceX launches its Falcon Heavy rocket from Kennedy Space Center it will be the most powerful rocket since Saturn V last launched in 1973.

With a maximum thrust of 5.1 million pounds at liftoff, the Falcon Heavy could launch spacecraft, with or without crew on board, to the moon, Mars and beyond. How does this compare to currently operational rockets, rockets in development and launch vehicles that are no longer in action, like Saturn V and the Space Shuttle?

Standing at more than 20 stories tall, Falcon Heavy has three core boosters and 27 Merlin engines on the first stage of the rocket. Inside the nose cone, the rocket could launch payloads weighing as much as a jetliner airplane, with passengers, crew and their bags, or 64 metric tons.

On Monday, one day ahead of the planned Falcon Heavy test flight, SpaceX CEO Elon Musk said the rocket could actually be modified, adding two more boosters.

"Falcon Heavy can be as powerful as we need it," he said. "Call it Falcon Super Heavy."

Only NASA's Space Launch System, which is still in development, will be able to launch more weight into space.

No company or agency as yet has contracted a launch using a Falcon Heavy rocket that would fully test those perimeters. SpaceX currently has five Falcon Heavy launches on the company manifest, one included the test flight set for the first week in February and the four others are contracted by the U.S. Air Force and satellite manufacturers.

Below is a breakdown of past, current and future rockets by their payload capacity launching to low-Earth orbit and maximum thrust at liftoff.